Trans-septal sheath with splitting dilating needle and method for its use

ABSTRACT

A device useful for accessing the left atrium is provided. The device comprises an elongated tubular body and a dilating tip. The tubular body has an axis, a proximal end, a distal end and a lumen longitudinally extending therethrough. The dilating tip is slidably mounted on the distal end of the tubular body. The dilating tip comprises a segmented surface that is generally transverse to the axis of the tubular body, and a generally rigid tube extending distally from the segmented surface and having a sharp distal end. Distal movement of the tubular body relative to the dilating tip exerts a force on the segmented surface to thereby open the segmented surface.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No.10/618,033, filed Jul. 11, 2003 now U.S. Pat. No. 8,021,387, the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to a device that functions as both aguiding sheath and dilating needle.

BACKGROUND OF THE INVENTION

Electrophysiology catheters are commonly used for mapping electricalactivity in a heart. Electrophysiology is a specialty within the fieldof cardiology for diagnosis and treatment of electrical abnormalities ofthe heart. By mapping the electrical activity in the heart, ectopicsites of electrical activation or other electrical activation pathwaysthat contribute to heart malfunctions may be detected. This type ofinformation may then allow a cardiologist to intervene and destroy themalfunctioning heart tissues. Such destruction of heart tissue istypically performed using an ablation catheter and is referred to asablation. Ablation is a rapidly growing field within electrophysiologyand obviates the need for maximally invasive open heart surgery.

Occasionally, an electrical abnormality occurs in a location that isdifficult to reach with standard catheter capabilities. A left atrium ofa heart is one such location. When an electrical abnormality occurs in aleft atrium, a dilation catheter, or dilator, may be insertedpercutaneously, fed through one or more major blood vessels, andinserted into a right atrium of the heart. A needle may then be feedthrough the dilator and inserted into and through the atrial septum topuncture the atrial septum to allow access to the left atrium for atherapeutic catheter, such as an ablation catheter.

A current technique for puncturing the atrial septum includespositioning a dilator adjacent to an area of the atrial septum that isdesired to be punctured (typically at the fosa ovalis), inserting aseparate needle into the dilator, feeding the needle through the dilatoruntil the needle protrudes beyond the dilator, and puncturing the atrialseptum with the needle. This technique has several disadvantages. Forexample, locating the desired puncture site and then inserting andfeeding a separate needle into the dilator increases the procedure time,and increases the likelihood that the dilator will be inadvertentlymoved before the needle reaches the desired puncture site, thusrequiring a repositioning of the dilator. If the repositioning isperformed with the needle inside the dilator, the possibility exists forthe needle to slide out of the dilator and damage venous or atrialstructures. If the needle is removed during repositioning, proceduretime is again extended during reinsertion and re-feeding of the needleinto the dilator, and an inadvertent movement of the dilator duringreinsertion and re-feeding of the needle again exists.

Another more serious disadvantage of the current technique is that, todilate the hole enough for a guiding sheath to fit through with thedilator, the sharp needle has to be advanced ten to twenty millimetersinto the left atrium, which would bring the sharp edge dangerously closeto the superior wall of the left atrium, which might result inperforation, especially if the left atrium is small. Moreover, a forcein a distal direction is required to insert the needle into and throughthe atrial septum, yet there is no means for controlling the maximumprotrusion of the needle from the dilator. As a result, a tendency isfor the operator to continue to apply a forward force to the needle evenafter the needle has crossed the atrial septum, thus risking damage tovenous or atrial structures in the left atria or even cardiac punctureif the needle protrudes too far from the dilator.

Yet another disadvantage of the existing technique is that, when thesheath is advanced into the left atrium, it is typically placed at leastabout ten millimeters beyond the septum wall. If it is advanced lessthan ten millimeters, it might fall out of the left atrium. This givescatheters and other devices that go through the sheath very limitedaccess to the septum from the left side. If a procedure requires mappingor ablation on the left septum, it is almost impossible to perform withconventional sheaths.

SUMMARY OF THE INVENTION

The present invention addresses the above-referenced problems byproviding a device useful for accessing the left atrium. The devicecomprises an elongated tubular body and a dilating tip. The tubular bodyhas an axis, a proximal end, a distal end and a lumen longitudinallyextending therethrough. The dilating tip is slidably mounted on thedistal end of the tubular body. The dilating tip comprises a segmentedsurface that is generally transverse to the axis of the tubular body,and a generally rigid tube extending distally from the segmented surfaceand having a sharp distal end. Distal movement of the tubular bodyrelative to the dilating tip exerts a force on the segmented surface tothereby open the segmented surface.

In another embodiment, the invention is directed to a device useful foraccessing the left atrium comprising an elongated tubular body and adilating tip. The tubular body has an axis, a proximal end, a distal endand a lumen longitudinally extending therethrough. The dilating tip isslidably mounted on the distal end of the tubular body. The dilating tipcomprises a ring mounted in surrounding relating to the distal end ofthe tubular body and a segmented surface that is generally transverse tothe axis of the tubular body. The segmented surface comprises three ormore segments, each segment being hingedly attached to the ring. Thedilating tip further comprises a generally rigid tube extending distallyfrom the segmented surface. The tube has a sharp distal end and issegmented into three or more segments. Distal movement of the tubularbody relative to the dilating tip exerts a force on the segmentedsurface to thereby open the segmented surface.

In another embodiment, the invention is directed to a method foraccessing the left atrium of a patient. The method comprises insertingthe dilating tip of a device as described above into the right atrium ofthe patient. The atrial septum is punctured with the tube of thedilating tip to create a trans-septal hole. The tubular body is advanceddistally relative to the dilating tip to open the segmented surface andintroduce a distal portion of the tubular body into the left atriumthrough the trans-septal hole.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view of a device according to the invention;

FIG. 2 is a side view of a dilating tip according to the invention;

FIG. 3 is a side view of the dilating tip of FIG. 2 turned 90°;

FIG. 4 is a perspective view of a dilating tip mounted on the distal endof a tubular body, where the dilating tip is slightly open; and

FIG. 5 is a perspective view of a dilating tip mounted on the distal endof a tubular body, where the dilating tip is almost entirely open.

DETAILED DESCRIPTION

The invention is directed to a device that serves as a guiding sheath, adilator and a dilator needle. The device comprises a generally-flexibleelongated tubular body 10 having proximal and distal ends and a lumen 12extending longitudinally therethrough. In the depicted embodiment, thelumen 12 is a central lumen. The tubular body 10 can be of any suitableconstruction. Preferably the tubular body 10 comprises polyethylene withbarium sulfate. If desired, a lubricious coating can be provided insideor over the tubular body 10. A suitable coating comprises silicone, suchas MDX4-4159, a mixture of amino functional polydimethylsiloxanecopolymer in mixed aliphatic and isopropanol solvents (commerciallyavailable from Dow Corning™, Midland, Mich.).

The tubular body 10 has an outer diameter ranging from about 2 mm toabout 4 mm, preferably from about 2.5 mm to about 3.5 mm, still morepreferably about 3 mm. Preferably the tubular body 10 has a lengthranging from about 60 cm to about 100 cm.

On the distal end of the tubular body 10 is slidably mounted a dilatingtip 14. As shown in FIGS. 2 to 5, the dilating tip 14 comprises asegmented surface 16 that is generally transverse to the axis of thetubular body 10, and a generally rigid tube 18 extending distally fromthe segmented surface. In the depicted embodiment, the dilating tip 14is generally funnel-shaped with the segmented surface 16 being generallyround and angled from its outer edge to its center, as best shown inFIGS. 2 and 3. The depicted segmented surface 16 comprises threepie-shaped segments 20, all of equal size. As will become apparent, theprecise number, shape and size of the segments 20, as well as theoverall shape of the dilating tip, can vary as desired. For example, thesegmented surface 16 can be generally flat rather than angled, althoughthe angled surface is particularly desirable for dilating the septumonce the septum has been punctured, as described further below.

Preferably the dilating tip 14 is made from a material having shapememory. A particularly suitable material for this purpose is a memoryalloy of a nickel-titanium composition known as nitinol. Type 55nitinol, made of 55% by weight nickel and 45% titanium, and type 60nitinol, made of 60% by weight nickel and 40% titanium, as well asvarious ternary and quaternary compositions of nitinol, can be used inthe invention.

The dilating tip 14 further comprises a ring 22 slidably mounted overthe outside of the tubular body 10 to which the segments 20 areattached. In the depicted embodiment, each of the segments 20 has anouter edge 21 that is hingedly attached to the ring 22 at a hingedjunction 24. The segments 20 each also have two free edges 23 that arenot attached to any of the other segments or to the ring 22. The ring 22preferably has an inner diameter slightly greater than the outerdiameter of the tubular body 10, and the inner diameter preferablyranges from about 2 mm to about 3 mm. As the ring 22 is moved proximallyrelative to the tubular body 10, the distal end of the tubular bodycontacts the inner surfaces of the segments 20 of the segmented surface16, thereby pushing the segments distally 20. Because only the outeredges 21 of the segments 20 are hingedly attached to the ring 22, thetubular body 10 pushes the segments open, as best shown in FIG. 5.

As noted above, an elongated generally rigid tube 18 extends distallyfrom the segmented surface 16. As best shown in FIG. 2, the generallyrigid tube 18 has a sharp distal end 24. As used herein, the terms“generally rigid” and “sharp” when referring to the tube 18 and distalend 24, respectively, mean that the tube is sufficiently rigid and thedistal end is sufficient sharp so that the tube can be used to puncturethe septum, as described in more detail below. In the depictedembodiment, the tube 18 is depicted as generally cylindrical, but othershapes are contemplated within the invention, such as a tube having agenerally square or hexagonal cross-sectional area. The tube 18preferably has a length ranging from about 2 mm to about 6 mm, morepreferably from about 3 mm to about 5 mm. The tube 18 preferably has anouter diameter ranging from about 0.6 mm to about 1 mm, more preferablyfrom about 0.7 mm to about 0.8 mm.

In the depicted embodiment, the tube 18 is also segmented into threetube segments 26. Each tube segment 26 has a proximal end attached to asegment 20 and a free distal end. With this design, when the tubularbody 10 is moved distally to open the segments 20, the tube segments 26also separate and open with the segments 20. Other arrangements arecontemplated within the scope of the invention. For example, the tube 18could be a unitary (non-segmented) structure that is attached to onlyone of the segments 20.

In the depicted embodiment, the distal end of the tubular body 10 isgenerally straight. However, in some instances it may be advantageousfor a portion of the distal end of the tubular body 10 to have apre-formed curve. For example, due to the angle of the right atriumopening with respect to the atrial septum, when a tubular body 10 havinga straight distal end is inserted into the right atrium and advanced toa position adjacent to the atrial septum, the tube 18 is likely to beangled with respect to the atrial septum. In such an instance, it may bedesirable for the distal end of the tubular body 10 to have a pre-formedcurve to allow the tube 18 to be situated in a more perpendiculararrangement relative to the atrial septum, thus allowing for a cleanerpuncture of the septum.

In order to facilitate relative movement of the tubular body 10 relativeto the dilating tip 14, a slidable ring 28 or other slidable member ismounted on the proximal end of the tubular body. The slidable ring 28 isconnected to the ring 22 of the dilating tip 14 with a plurality ofwires 30. Thus, in use, the physician can pull the slidable ring 28proximally relative to the tubular body 10, thereby pulling the dilatingtip 14 proximally relative to the tubular body, and thus opening thesegmented surface 16 of the dilating tip. Other mechanisms forfacilitating relative movement of the tubular body 10 and dilating tip14 are considered within the scope of the invention.

In the depicted embodiment, a latch mechanism is provided to hold theslidable ring 28 in place relative to the tubular body 10 when thedilating tip 14 is in an open position. The latch mechanism includes oneor more latches 32 that are fixedly attached to the proximal end of thetubular body 10 proximal to the slidable ring 28. The latches 32 arereceived by notches 34 in the slidable ring 28, to thereby temporarilylock the slidable ring in place. The presence and arrangement of thelatch mechanism is not critical to the invention.

Additionally, a pressure valve 36 is mounted on the proximal end of theon the tubular body 10 such that the pressure in the tubular body may bemonitored, as discussed further below.

In use, a guidewire (not shown), such as a 0.032 inch diameterguidewire, is positioned within the right atrium of a patient's heart.The device of the invention is then passed over the guidewire, with theguidewire extending through the lumen 12 of the tubular body 10 andthrough the elongated tube 18. The guidewire preferably includes anatraumatic distal tip.

The distal end of the device is passed over the guidewire and introducedinto the right atrium. If desired, the dilating tip 14 and/or the distalend of the tubular body 10 can comprise tungsten or other radiopaquematerial, which appears dark under fluoroscopy, allowing the distal endof the device to be easily viewed under fluoroscopy. Once the dilatingtip 14 is in the right atrium, a puncture site may be located. Thelimbus of the fossa ovalis provides a good reference point for locatingan optimal puncture site. Often, the ridge of the limbus of the fossaovalis can be felt by the operator using the distal end of the dilatingtip 14. Just below the limbus is the central atrial septum, which tendsto be the thinnest area of the septum, and is therefore the preferredarea to penetrate. When the central atrial septum is located with thedilating tip 14, the tube 18 may be placed directly adjacent to andabutting the central atrial septum and pushed distally against theseptum to thereby puncture of the septum.

As noted above, the proximal end of the tubular body 10 may be attachedto a pressure valve 26 such that the pressure in the tubular body may bemonitored. The pressure in the right atrium is different then thepressure in the left atrium. Therefore, by monitoring the pressure inthe tubular body 10, the operator can determine when the needle hasentered the left atrium, as is generally known in the art.

Once the tube 18 of the dilating tip 14 is in the left atrium, theslidable ring 28 on the proximal end of the tubular body 10 is moveddistally relative to the tubular body. As a result, the distal end ofthe tubular body 10 is moved distally relative to the dilating tip 14 tothereby push open the segmented surface 16. This action dilates thetrans-septal hole created with the tube 18 to thereby permit the distalend of the tubular body to be introduced into the left atrium.Alternatively, the segmented surface 16 can be moved distally into theleft atrium to dilate the trans-septal hole, particularly when thesegmented surface is angled as shown in FIGS. 2 and 3, before thetubular body 10 is moved distally to open the segmented surface.

Once the segmented surface 16 is opened within the left atrium, thelatches 32 can then be used to maintain the slidable ring 28 in place sothat the dilating tip 14 is kept in an open configuration. If theslidable ring 28 is not locked in place, the tubular body 10 may tend toslip proximally out of the left atrium. With the distal end of thetubular body 10 within the left atrium, the tubular body may then beused to guide a therapeutic catheter, such as an ablation catheter, intothe left atrium. Thus, the tubular body 10 serves as a guiding sheathfor this purpose.

The inventive device offers numerous advantages over devices previouslyused for trans-septal access. Notably, the inventive device avoids theneed for a needle and dilator, as all of the functions are performed bythe single device of the invention, thereby simplifying the process. Incontrast, traditional methods require at least three different devicesworking together, thereby requiring numerous exchanges and management offluids aspiration and pressure monitoring through more than one lure.The inventive device also avoids the need to change the pressuremonitoring from a needle to a sheath.

Further, the limited length of the tube 18 avoids damage that cantypically be caused when a needle is used and advanced too far into theleft atrium. Additionally, the dilating tip 14, when in an openposition, acts as a backstop to prevent the tubular body 10 from fallingout of the left atrium. Therefore, it is not necessary to advance thetubular body 10 as far into the left atrium as is required withtraditional guiding sheaths. As a result, the tubular body 10, whichserves as a guide mechanism for a treatment catheter, does notsignificantly interfere with the operator's ability to manipulate thetreatment catheter within the left atrium. In particular, the treatmentcatheter can be used to access more of the left atrium than with atraditional guiding sheath.

The preceding description has been presented with references topresently preferred embodiments of the invention. Persons skilled in theart and technology to which this invention pertains will appreciate thatalterations and changes in the described structures can be practicedwithout meaningfully departing from the principle, spirit and scope ofthis invention. Accordingly, the foregoing description should not beread as pertaining only to the precise structures described and shown inthe accompanying drawings, but rather should be read as consistent withand as support for the following claims, which are to have their fullestand fairest scope.

What is claimed is:
 1. A method for accessing the left atrium of apatient comprising: inserting a dilating tip of a device into the rightatrium of the patient, the device comprising: an elongated tubular bodyhaving an axis, a proximal end, a distal end and a lumen longitudinallyextending therethrough; and the dilating tip slidably mounted on thedistal end of the tubular body and comprising: a segmented surface thatis generally transverse to the axis of the tubular body, the segmentedsurface comprising a plurality of segments having proximal and distalends, wherein the plurality of segments is configured to move between aclosed configuration in which the segments combine to form the segmentedsurface and an open configuration in which the segments separate fromone another, a plurality of generally rigid tube segments extendingdistally from the segmented surface, each tube segment having a proximalend affixed to the distal end of a corresponding one of the plurality ofsegments of the segmented surface and extending distally therefrom,wherein when the plurality of segments of the segmented surface is inthe closed configuration, the plurality of generally rigid tube segmentscombine to form a generally rigid tube having a sharp distal endconfigured to puncture tissue, and when the plurality of segments of thesegmented surface are in the open configuration, the plurality ofgenerally rigid tube segments have free distal ends that are separatefrom each other, and a ring slidably mounted on the tubular body,wherein the proximal ends of the segments of the segmented surface arehingedly attached to the ring; wherein proximal movement of the ringrelative to the elongated tubular body exerts a force on the segmentedsurface to thereby open the segmented surface; puncturing the atrialseptum with the sharp distal end of the dilating tip to create atrans-septal hole; advancing the ring proximally relative to theelongated tubular body to open the segmented surface and introduce adistal portion of the elongated tubular body into the left atriumthrough the trans-septal hole.
 2. A method according to claim 1, furthercomprising advancing at least a portion of the dilating tip through thetrans-septal hole prior to advancing the ring proximally relative to theelongated tubular body.
 3. The method of claim 1, further comprisingmonitoring the pressure in the elongated tubular body.
 4. The methodaccording to claim 1, wherein the elongated tubular body is generallycylindrical.
 5. The method according to claim 1, wherein the segmentedsurface comprises three or more segments.
 6. The method according toclaim 1, wherein the dilating tip is generally funnel-shaped.
 7. Themethod according to claim 1, wherein the generally rigid tube has alength ranging from about 2 mm to about 6 mm.
 8. The method according toclaim 1, wherein the generally rigid tube has a length ranging fromabout 3 mm to about 5 mm.
 9. The method according to claim 1, whereinthe generally rigid tube has an outer diameter ranging from about 0.6 mmto about 1 mm.
 10. The method according to claim 1, wherein thegenerally rigid tube has an outer diameter ranging from about 0.7 mm toabout 0.8 mm.
 11. The method according to claim 1, wherein the dilatingtip comprises nitinol.
 12. The method according to claim 1, wherein thedevice further comprises a wire extending proximally from the ring tonear the proximal end of the elongated tubular body to affect proximalmovement of the ring relative to the elongated tubular body.
 13. Themethod according to claim 12, wherein the device further comprises aslidable member on the proximal end of the elongated tubular body, theslidable member being connected to the wire so that proximal movement ofthe slidable member pulls the wire and causes proximal movement of thering relative to the elongated tubular body.
 14. The method according toclaim 13, wherein the device further comprises a latch for maintainingthe position of the slidable member relative to the elongated tubularbody when the dilating tip is in an open configuration.
 15. The methodaccording to claim 1, wherein the device further comprises a pressurevalve at or near the proximal end of the elongated tubular body.
 16. Amethod for accessing the left atrium of a patient comprising: insertinga dilating tip of a device into the right atrium of the patient, thedevice comprising: an elongated tubular body having an axis, a proximalend, a distal end and a lumen longitudinally extending therethrough; thedilating tip slidably mounted on the distal end of the tubular body andcomprising: a ring mounted in surrounding relation to the distal end ofthe tubular body; a segmented surface that is generally transverse tothe axis of the tubular body, the segmented surface comprising three ormore, segments, each segment being hingedly attached to the ring,wherein the three or more segments are configured to move between aclosed configuration in which the segments combine to form the segmentedsurface and an open configuration in which the segments separate fromone another; three or more generally rigid tube segments, each tubesegment having a proximal end affixed to a distal end of a correspondingone of the three or more segments of the segmented surface and extendingdistally therefrom, wherein when the three or more segments of thesegmented surface are in the closed configuration, the three or moregenerally rigid tube segments combine to form a generally rigid tubehaving a sharp distal end configured to puncture tissue, and when thethree or more segments of the segmented surface are in the openconfiguration, the three or more generally rigid tube segments have freedistal ends that are separate from each other; and a slidable memberconnected to the ring of the dilating tip, wherein proximal movement ofthe slidable member relative to the elongated tubular body exerts aforce on the segmented surface to thereby open the segmented surface;puncturing the atrial septum with the sharp distal end of the generallyrigid tube of the dilating tip to create a trans-septal hole; andadvancing the slidable member proximally relative to the elongatedtubular body to open the segmented surface and introduce a distalportion of the elongated tubular body into the left atrium through thetrans-septal hole.
 17. The method according to claim 16, wherein thedevice further comprises: a wire having a distal end attached to thering of the dilating tip and a proximal end attached to the slidablemember; wherein proximal movement of the slidable member pulls the wireand causes proximal movement of the dilating tip relative to the tubularbody.